What is a DIN 71802 angle joint?
It is a ball stud and a ball socket that snap together. The stud has a ball on one end. The socket has a cup that is pressed over the ball and held there by a ring inside it. "Angle" refers to the layout: the stud sits at 90° to the rod it connects to.
DIN 71802 is the German standard that sets the mounting dimensions for these joints. The joint is assembled from two parts that have standards of their own: the socket is the DIN 71805 part, and the stud (ball shank) is the DIN 71803 part. A rod end is a different part: its ball sits inside a housing and is held by a bolt through the ball. See K03-Q1-02 and Q1-26.
What do the letters mean?
The letters name the type of stud and say whether a safety clip is fitted.
| Form | Stud | Safety clip | Notes |
|---|---|---|---|
| C | Threaded stud, usually with wrench flats and a hex nut | No | Listed by most makers |
| CS | As C | Yes | Same joint as C, plus the clip |
| B | Stud with a rivet end, fixed to a part by riveting instead of a thread | No | Listed by most makers |
| BS | As B | Yes | Same joint as B, plus the clip |
| A, AS | Threaded stud without wrench flats | No / Yes | Listed in parts libraries such as CADENAS |
Form C differs from form CS only in lacking the safety clip, and B differs from BS in the same way. C and CS have a threaded stud; B and BS have a rivet stud.
Some makers add an N for stainless steel, as in CN and CSN. That letter is a maker suffix, not a DIN form letter.
SYZ's CS series is an example of the CS form: its spec page lists eight metric sizes from M5 to M16, with a spring-steel retention clip.
Is "Form A" always the same thing?
No. The socket has its own forms. DIN 71805 sockets come as form A and form B. Form A has the snap ring but no groove; form B has a groove for mounting a clip. The safety clip itself is DIN 71805 form S.
So "form A" on a joint (DIN 71802) and "form A" on a socket (DIN 71805) are different things. When you order, give the full designation.
What does a safety clip do?
It adds a second line of holding between the socket and the ball.
The first line is the snap ring inside the socket. On assembly the ball is pushed through the ring, and afterwards the ring stands in the way of the ball coming back out. If that retaining force is not enough, a safety clip fitted over the socket adds to it.
The clip does not do two other jobs. It does not stop a loose thread from unwinding, which is a lock-nut matter (Q1-23). And it does not make an undersized joint stronger.
Terms differ between makers. The ring inside is the snap ring or circlip. The outside part is the safety clip, safety catch or DIN 71805 form S, and some makers call it a circlip too. Check the part drawing.
When do you need a safety clip?
Fit one when any of these apply:
- The joint hangs below its stud. The abstract of DIN 71802:1992-04 recommends that angle joints without a safety clip should not be mounted in a hanging position. It names forms A and B. The clipped forms exist for exactly this case.
- A pull could exceed the catalog pull-off value. Catalogs list a minimum pull-off force of 30 to 100 N for a new part, pulled along the stud, depending on ball size (Q1-05). Shock peaks count, not just the steady load.
- Vibration or shock is present and a separation would cause damage or injury. This is an engineering judgment; no standard sets a threshold for it.
You can usually do without one when the joint is supported from below, loads are small, and a separation would be harmless. In that case the extra tilt may be worth more.
How much tilt does the clip cost?
About 3°. Ganter's catalogue (also sold as JW Winco) lists the angle of rotation as 15° for types with a safety catch (CS, BS) and 18° for types without (C, B). Another maker lists ±18° for its CS joints. Catalogs state the angle in different ways, one side or total, so use the maker's drawing for your part. Q1-09 covers tilt in full.
How do you read a part number?
A typical designation is "DIN 71802 CS 16 – M10" (a common catalogue style). It reads as standard, form, ball diameter in mm, thread. This one is a form CS joint with a 16 mm ball and an M10 thread.
Suffixes add detail. In catalogue listings, "L" after the thread (M5L) means a left-hand thread, and "F" (M14F) means a fine thread, M14×1.5.
How does a vehicle mount change the choice of angle joint?
Shift linkages, throttle linkages and small control levers on vehicles, ATVs and UTVs are common homes for angle joints, and they combine the conditions the clip exists for: constant vibration, shock when the vehicle bounces or a lever is knocked, and a layout that may put the socket below its stud depending on where the engine and lever sit. The hanging-mount recommendation therefore applies more often than it does on a bench machine, and a clipped form (CS, BS) is the sensible starting point for any vehicle link whose separation would cost the driver control.
The price is the 3° of tilt, and on an engine-mounted linkage that tilt may already be used by the engine rocking against the chassis (Q1-09). Mud and sand also work into the gap between socket and ball, so a cap is worth fitting; a cap takes tilt too, so check the angle with the clip and cap both fitted (Q1-11).
Throttle, brake and steering links are safety parts. Whether a particular angle joint is acceptable on one is for the vehicle maker to say; a catalogue form letter does not settle it. SYZ's small ball joint page covers the CS clipped form and the rest of the range.